MAX6640ATE 查看數據表（PDF） - Maxim Integrated

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MAX6640ATE

2-Channel Temperature Monitor with Dual Automatic PWM Fan-Speed Controller

Maxim Integrated 

2-Channel Temperature Monitor with Dual

Automatic PWM Fan-Speed Controller

A

B

C

D

EF

G

tLOW tHIGH

SCL

H

IJK

LM

SDA

tSU:STA tHD:STA

tSU:DAT

A = START CONDITION

B = MSB OF ADDRESS CLOCKED INTO SLAVE

C = LSB OF ADDRESS CLOCKED INTO SLAVE

D = R/W BIT CLOCKED INTO SLAVE

E = SLAVE PULLS SMBDATA LINE LOW

F = ACKNOWLEDGE BIT CLOCKED INTO MASTER

G = MSB OF DATA CLOCKED INTO SLAVE

H = LSB OF DATA CLOCKED INTO SLAVE

Figure 2. SMBus Write Timing Diagram

tSU:STO tBUF

I = MASTER PULLS DATA LINE LOW

J = ACKNOWLEDGE CLOCKED INTO SLAVE

K = ACKNOWLEDGE CLOCK PULSE

L = STOP CONDITION

M = NEW START CONDITION

A

B

C

D

EF

G

tLOW tHIGH

SCL

H

I JK

LM

SDA

tSU:STA tHD:STA

A = START CONDITION

B = MSB OF ADDRESS CLOCKED INTO SLAVE

C = LSB OF ADDRESS CLOCKED INTO SLAVE

D = R/W BIT CLOCKED INTO SLAVE

E = SLAVE PULLS SMBDATA LINE LOW

tSU:DAT

tHD:DAT

F = ACKNOWLEDGE BIT CLOCKED INTO MASTER

G = MSB OF DATA CLOCKED INTO MASTER

H = LSB OF DATA CLOCKED INTO MASTER

I = MASTER PULLS DATA LINE LOW

Figure 3. SMBus Read Timing Diagram

tSU:STO tBUF

J = ACKNOWLEDGE CLOCKED INTO SLAVE

K = ACKNOWLEDGE CLOCK PULSE

L = STOP CONDITION

M = NEW START CONDITION

SMBus Digital Interface

From a software perspective, the MAX6640 appears as

a set of byte-wide registers. This device uses a stan-

dard SMBus 2-wire/I2C-compatible serial interface to

access the internal registers. The MAX6640 has a fixed

slave address of 0101111.

The MAX6640 employs four standard SMBus protocols:

write byte, read byte, send byte, and receive byte

(Figures 1, 2, and 3). The shorter receive byte protocol

allows quicker transfers, provided that the correct data

register was previously selected by a read byte instruc-

tion. Use caution with the shorter protocols in multimas-

ter systems, since a second master could overwrite the

command byte without informing the first master.

Table 3 details the register addresses and functions,

whether they can be read or written to, and the power-

on reset (POR) state. See Tables 4–8 for all other regis-

ter functions and the Register Descriptions section.

Temperature Reading

Temperature data can be read from registers 00h and

01h. The temperature data format for these registers is

8 bits, with the LSB representing 1°C (Table 1) and the

MSB representing +128°C. The MSB is transmitted first.

Three additional temperature bits provide resolution

down to 0.125°C and are in the channel 1 extended

temperature (05h) and channel 2 extended temperature

(06h) registers. All values below 0°C clip to 00h.

The MAX6640 employs a register lock mechanism to

avoid getting temperature results from the temperature

register and the extended temperature register sam-

pled at two different time points. Reading the extended

register stops the MAX6640 from updating the tempera-

ture register for at least 0.25s, unless there is a temper-

ature register read before the scheduled update. This

allows enough time to read the main register before it is

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